Unstable Footing’s effect causes damage from all sources to be unpreventable, not just damage from Unstable Footing itself.

10/1/2009

If damage can’t be prevented, damage prevention shields don’t have any effect. If a prevention effect has an additional effect, the additional effect will still work (if possible). Spells that create prevention effects can still be cast, and abilities that create prevention effects can still be activated.

10/1/2009

If damage can’t be prevented, static abilities that prevent damage (including protection abilities) don’t do so. If they have additional effects that don’t depend on the amount of damage prevented, those additional effects will still work. Such effects are applied only once per source of damage.

10/1/2009

Effects that replace or redirect damage without using the word “prevent” are not affected by Unstable Footing.

10/1/2009

If a creature is dealt lethal damage, it can still regenerate. If it does, the damage marked on it will be removed from it.

10/1/2009

If Unstable Footing is kicked and the targeted player is an illegal target by the time it resolves, the entire spell doesn’t resolve. Damage can still be prevented.